The field of the disclosure relates generally to gas engines, and more particularly, to methods and systems for using pressure wave modeling to estimate in-cylinder pressure within gas engines.
Many gas engines include an intake system including an intake manifold and a plurality of cylinders. Such intake manifolds include an open end to receive air and a closed end to keep air captured. Gas may be injected at an inlet valve on each of the plurality of cylinders. In such gas engines, fuel is combusted to produce power using a generator.
In many known gas engines, preferred control of combustion involves controlling and monitoring an air-to-fuel ratio. Such an air-to-fuel ratio is be referred to as “AFR” or λ. In order to control for λ, the amount of fuel injected is determined relative to the amount of air present in the gas engine. Therefore, in such gas engines it is important to accurately estimate the quantity of air in each cylinder that receive fuel injections. Many known methods of such estimations utilize a sensor-based pressure measurement at each cylinder and a pressure measurement at the intake manifold.
However, such estimations are often inaccurate. First, in such known methods it is often assumed that the pressure is constant throughout the intake manifold. Such an assumption is inaccurate due to pressure waves created by the opening and closing of inlet valves. Second, the sensor-based pressure measurements are inaccurate because the turbulent conditions within the intake manifold cause errors in the sensors. Accordingly, improved methods of estimating in-cylinder pressure and air quantity are desired to improve the control of λ.